The piezoelectric vibrator of this kind, such as a tuning fork type quartz vibrator is generally known as a signal source ticking a clock rate of a wrist watch, and has been adopted as a synchronizing signal source of portable electronic devices in recent years. Further miniaturization of quartz vibrators is required with miniaturization of such electronic devices.
The configuration of a tuning fork type quartz vibrator is described in Patent Document 1. In the configuration of the tuning fork type quartz vibrator shown in FIG. 9, tuning fork arms 2a and 2b serving as a pair of vibrating arms are provided on a base 1, and grooves 3 are provided on both main surfaces of the respective turning fork arms 2a and 2b. Excitation electrodes to excite tuning fork vibration based on winding vibrations of the respective tuning fork arms 2a and 2b are provided on the grooves 3 and both side surfaces of the respective tuning fork arms 2a and 2b. The excitation electrodes are connected so that a side surface of one tuning fork arm 2a and the inside of the groove 3 of the other tuning fork arm 2b are at the same potential, and the side surface of the other tuning fork arm 2b and the inside of the groove 3 of the other tuning fork arm 2a are at opposite potentials when electric charges are given to the tuning fork type vibrator.
By using such a tuning fork type quartz vibrator, an electric field intensity in the X-axis direction (width direction of the tuning fork arm) is increased compared with the case of not forming the grooves 3. Accordingly, a winding vibration in the Y-axis direction (in the length direction of a tuning fork arm) mutually expanding and contracting in the opposite direction between both side surfaces of the respective tuning fork arms 2a and 2b is strongly excited.
By configuring the vibrator in this manner, vibration loss of the tuning fork arms 2a and 2b becomes low, and therefore, it is possible to obtain a piezoelectric vibrator having a basically favorable CI (crystal impedance) value.
However, further decrease in the CI value has been required due to a request for efficiency of the power consumption in electronic parts using the quartz vibrator. Furthermore, since the tuning fork type quartz vibrator described in the above-described Patent Document 1 has grooves on the tuning fork arms as described above, shock resistance is lessened when the quartz vibrator is miniaturized, and shock resistance against a drop or the like is low, which may possibly cause trouble such as damage when manufacturing electronic parts and so on.
Patent Document 1
Patent Application Laid-open No. 2002-261575